Breast carcinoma in situ (BCIS) is an increasingly common diagnosis with important implications for future morbidity and quality of life. We propose to extend our highly successful population-based study of BCIS to examine how recurrence and quality of life in BCIS survivors is associated with modifiable lifestyle factors. Specifically we will investigate: 1) risk factors for recurrence, including SERMs, postmenopausal hormones, behaviors such as physical activity and diet, and their interaction with histopathologic characteristics; and 2) quality of life in relation to treatment, recurrence, and time since diagnosis among BCIS survivors. We will evaluate these relationships among 1,105 incident cases of BCIS interviewed in our current study between 1997-2001 (Phase 1), and an additional 1,487 new cases to be interviewed 2002-2005 (Phase 2) between the ages of 20 and 74. All cases are identified from Wisconsin's statewide tumor registry; based on previous experience, we anticipate high participation rates (over 85 percent) in our telephone interview. The interview will provide information on quality of life (using the SF-36), lifestyle factors--including weight, alcohol intake, diet, physical activity, and medication use--and cancer treatment. Annual newsletters will be mailed to all cohort members to update any address and health status changes, and follow-up interviews will be conducted biennially to identify recurrences, second primaries, new treatments, as well as changes in quality of life and risk factors. We anticipate 232 recurrences over the follow-up period (median 5 years post initial diagnosis), as verified by information collected from treating physicians and the statewide tumor registry. By utilizing an efficient, well-established mechanism for enrolling, interviewing, and re-contacting cases, this study will provide timely and generalizable new information. There is an urgent need to understand how women may actively minimize the risk of recurrence and how this diagnosis impacts upon the quality of women's lives. The proposed population-based cohort offers a powerful opportunity to inform women and physicians as they consider the trade-offs currently inherent in BCIS treatment.